Carnivorous Plants

Venus's flytrap

Most carnivorous plants eat flying, foraging, or crawling insects.
Those that live in or around water capture very small aquatic prey like mosquito larvae
and tiny fish. On rare occasions, some tropical carnivorous plants have
even been reported to capture frogs, or even rats and birds (although
these creatures were probably sick or already near death)! But don’t
worry, these plants pose no danger to humans, even if you fell asleep in a
whole bed of them.

Carnivorous plants tend to grow in places where the soil is thin or
lacking in nutrients like bogs and
rocky areas, so these plants must get some of their nutrients by trapping
and digesting animals, especially insects. More than 600 species and subspecies of
carnivorous plants have been identified, although some are now extinct.
The Venus’s-flytrap is
probably the most famous.

Catching a Meal

Just like other plants that need to attract other creatures to help
with things like pollination, carnivorous plants use different strategies
to attract their prey. Some are sweetly scented, others are brightly
colored, still others have parts that are sticky or slippery or designed
in a way that makes it hard for prey to escape. Once they have attracted
their dinner, carnivorous plants use five basic trapping strategies:

Pitfall traps (like pitcher plants), in which
the prey falls into a rolled leaf that contains a pool of digestive
enzymes and/or bacteria at the bottom;

Flypaper traps, that use a sticky glue substance to hold onto
unsuspecting insects;

Snap traps (like the Venus’s-flytrap), where the leaves
actually snap shut to create a plant prison;

Bladder traps, which use a bladder to suck in aquatic creatures;
and

Lobster-pot traps, which use inward-pointing hairs to force prey
towards the digestive enzymes.

The Venus’s-flytrap has long been an object of fascination (it
even stars in a movie!). How does the plant move? Does it have muscles?
Venus’s-flytraps aren’t the only type of carnivorous plant
that moves, but they are the most commonly known. When something touches
the trigger hairs on the edges of the leaves, the cells on the inside wall
of the trap transfer water to the outside walls, so the inside essentially
goes limp. This makes the leaf snap closed. Another way carnivorous plants
move can be observed in sundew plants, which have a long flypaper trap.
Once the prey gets stuck on the gluey tentacles, the tentacles embrace the
creature by growing faster on the outside than the inside. And they can do
this really fast. One species of sundew can bend 180º in only a
minute or so!

The Digestion Question

So once they catch their prey, how do these plants digest the meal?
Most carnivorous plants make their own digestive enzymes. Still others
depend on bacteria to produce these enzymes; the bacteria cause the
captured prey to rot and the plant absorbs the nutrients. Still other
plants rely on both their own enzymes and additional enzymes generated by
bacteria. Yet another method is even more unappetizing. Some carnivorous
plants use bugs and insects as helpers. For example, on carnivorous
sundews, assassin bugs crawl around and eat the insects that have been
captured. Then these bugs poop and the feces provide dinner for
the plant! Yuck!

Plant Eats Hollywood

Meat-eating plants have also captured the imagination of many writers
and filmmakers. One of the more well-known carnivorous plant stories is
Little Shop of Horrors, which was originally filmed in 1960, then
made into a Broadway musical, with a second Hollywood release in 1986.
This comedy/musical/horror film tells the story of a florist clerk who
discovers an unusual plant with a unique appetite…for human
blood.